Magnetron sputtering source

ABSTRACT

A sputter source has at least two electrically mutually isolated stationary bar-shaped target arrangements mounted one alongside the other and separated by respective slits. Each of the target arrangements includes a respective electric pad so that each target arrangement may be operated electrically independently from the other target arrangement. Each target arrangement also has a controlled magnet arrangement for generating a time-varying magnetron field upon the respective target arrangement. The magnet arrangements may be controlled independently from each other. The source further has an anode arrangement with anodes alongside and between the target arrangements and/or along smaller sides of the target arrangements.

This invention relates to a magnetron sputtering source, a vacuumchamber with such a source, a vacuum coating system with such a chamber,and in addition a process technique for such a system, as well as itsutilization.

In essence the present invention is based on the need for depositing onlarge-surface, in particular rectangular substrates with an area of atleast 900 cm², a film having a homogenous thickness distribution, bymeans of sputter coating, in particular also reactive sputter coating.Such substrates are in particular used in the manufacture of flatpanels, normally on glass substrates thinner than 1 mm, such as for TFTpanels or plasma display panels (PDP).

When magnetron sputter coating large surfaces, even larger sputtersurfaces and consequently larger targets are normally required unlessthe sputtering source and the substrate are moved relative to eachother. However, this results in problems with respect to

(a) uniformity of the process conditions on the large-surface target,with particular severity in reactive sputter coating

(b) erosion profile

(c) cooling

(d) strain on the large targets, in particular through atmosphericpressure and coolant pressure.

In order to solve the mechanical strain problem (d) relatively thicktarget plates have to be used which in turn reduces the magneticpenetration and consequently the electron trap effect for a givenelectrical input power. If the power is increased this results incooling problems (c), in particular because elaborate methods are neededfor achieving good contact between the target and the cooling medium,and also because of the obstruction resulting from the installations onthe back for accommodating the magnets. It is also known that inmagnetron sputtering, be it reactive or non-reactive, the targetarrangement normally consisting of a sputtering area defining targetplate made of the material to be sputtered and a bonded mounting plate,the target is sputter eroded along so-called "race tracks". On thesputter surface one or several circular erosion furrows are created dueto the tunnel-shaped magnet fields applied to the target along specificcourses, which produce circular zones with elevated plasma density.These occur due to the high electron density in the area of thetunnel-shaped circular magnetron fields (electron traps). Due to these"race tracks" an inhomogenous film thickness distribution occurs alreadyon relatively small-surface coating substrates arranged in front of themagnetron sputtering source. In addition the target material isinefficiently utilized because the sputter erosion along the "racetracks" removes little material from target areas outside these trackswhich results in a wave-shaped or furrow-shaped erosion profile. Becauseof these "race tracks" the actually sputtered surface even of a largetarget is small relative to the substrate surface. For eliminating theeffect of said "race tracks" on the coating it would be possible to movethe sputtering source and the substrate to be coated relative to eachother, as mentioned above, however, this results in a lower depositionrate per unit of time. If locally higher sputtering power is used,cooling problems are incurred in systems using relative motion.

In trying to achieve the desired goal basically four complexes ofproblems (a), (b), and (c), (d) are encountered whose individualsolutions aggravate the situation with respect to the others; thesolutions are mutually contradictory.

The objective of the present invention is to create a magnetronsputtering source through which said problems can be remedied, that canbe implemented in practically any size, and that is capable ofeconomically achieving a homogenous coating thickness distribution on atleast one large-surface substrate that is stationary relative to thesource. In addition to maintaining highly uniform process conditions thesource shall be suitable for sensitive reactive processes with highdeposition or coating rates. In reactive processes, inhomogenous "racetrack" effects lead to known, severe problems due to the large plasmadensity gradients.

This is achieved by the magnetron sputtering source according to thepresent invention in which at least two, preferably more than two,electrically isolated long target arrangements are placed parallel toeach other at a distance that is significantly smaller than the width ofthe target arrangement, where each target arrangement has its ownelectrical connections, and where in addition an anode arrangement isprovided. The targets of the target arrangements have preferably roundedcorners, following the "race track" paths.

On such a magnetron sputtering source according to the invention withindependently controllable electrical power input to the individualtarget arrangements, the film thickness distribution deposited on thesubstrate located above can already be significantly improved. Thesource according to the invention can be modularly adapted to anysubstrate size to be coated.

With respect to the overall arrangement the anode arrangementcan--unless it is temporarily formed by the target arrangementsthemselves--be located outside the overall arrangement but preferablycomprises anodes that are installed longitudinally between the targetarrangements and/or on the face of the target arrangement, butparticularly preferred longitudinally.

Also preferred is a stationary magnetron arrangement on the source; thelatter is preferably formed by a magnet frame that encircles all thetarget arrangements, or is preferably implemented with one frame eachencircling each target arrangement. Although it may be feasible andreasonable to implement the magnets on the frame(s), or on thestationary magnet arrangement at least partially by means ofcontrollable electric magnets, the magnets of the arrangement or theframe are preferably implemented with permanent magnets.

Through a corresponding design of said stationary magnet arrangement,preferably the permanent-magnet frames with respect to the magnet fieldthey generate on the immediately adjacent target arrangement, theaforementioned film thickness distribution on the substrate and theutilization efficiency of the long targets can be further enhancedthrough specific shaping of "race tracks".

Magnet arrangements are provided preferably below each of the at leasttwo target arrangements. These may be locally stationary and be fixedover time in order to create the tunnel shaped magnet field on each ofthe target arrangements. Preferably they are designed in such a way thatthey cause a time-dependent variation of the magnet field pattern on thetarget arrangements. With respect to the design and the generation ofthe magnet field pattern on each of the target arrangements according tothe invention, we refer to EP-A-0 603 587 or U.S. Pat. No. 5,399,253 ofthe same application, whose respective disclosure content is declared tobe an integral part of the present description.

According to FIG. 2 of EPO-A-0 603 587 the location of the magnetpattern and consequently the zones of high plasma density can be changedas a whole, but preferably it is not changed, or changed onlyinsignificantly, whereas according to FIGS. 2 and 3 of said applicationthe location of the apex--the point of maximum plasma density--ischanged.

For changing the location of the zones or the apex on the magnetarrangements, selectively controlled electric magnets--stationary ormovable--can be provided below each of the target arrangements, but farpreferably this magnet arrangement is implemented with driven movablepermanent magnets.

A preferred, moving magnet arrangement is implemented with at least twomagnet drums arranged longitudinally below the driven and pivot bearingmounted target arrangements, again preferably with permanent magnets asillustrated, for an individual target, in FIGS. 3 and 4 of EP-A-0 603587.

The magnet drums are driven with pendulum motion with a pendulumamplitude of preferably ≦τ/4. With respect to this technique and itseffect we again refer fully to said EP 0 603 587 or U.S. Pat. No.5,399,253 respectively which also in this respect are declared to be anintegral part of the present patent application description.

In summary, at least two driven and pivot bearing mounted permanentmagnet drums extending along the longitudinal axis of the targetarrangement are preferably provided.

In the preferred manner

with the electrical target arrangement supply

the field of said stationary magnet arrangement, in particular saidframes

with the field/time-variable magnet arrangement below each targetarrangement, preferably the magnet drums

a set of influencing variables is available which in combination allowextensive optimization of the deposited film thickness distribution, inparticular with respect to its homogeneity. In addition a high degree oftarget material utilization is achieved. Highly advantageous is thatpreferably--with shift of the magnet field apex on the targetarrangement--the plasma zones are not shifted in a scanning manner butthat within the zones the plasma density is changed through wobbling.

To allow maximum sputter power input the target arrangements areoptimally cooled by mounting them on a base where the target arrangementsurfaces facing the base are largely covered by cooling media channelswhich are sealed against the base by means of foils. Large-surface heatremoval is achieved because the pressure of the cooling medium pressesthe entire foil surface firmly against the target arrangements to becooled.

On the magnetron sputtering source according to the invention a base,preferably made at least partially from an electrically insulatingmaterial, preferably plastic, is provided on which in addition to saidtarget arrangements the anodes and, if existing, the stationary magnetarrangement, preferably permanent magnet frames, the magnet arrangementbelow the target arrangements, preferably the moving permanent magnetarrangements, in particular said drums, as well as the cooling mediumchannels, are accommodated. The base is designed and installed in such away that it separates the vacuum atmosphere and the external atmosphere.In this way the target arrangement can be more flexibly designed withrespect to pressure-induced mechanical strain.

Another optimization or manipulated variable for said large-surface filmthickness distribution is obtained by providing gas outlet openings,distributed on the longitudinal side of the target arrangement, whichopenings communicate with a gas distribution system. This makes itpossible to admit reactive gas and/or working gas with specificallyadjusted distribution into the process chamber above the sourceaccording to the invention of a vacuum treatment chamber or systemaccording to the invention.

The rectangular target arrangements are preferably spaced apart by max.15%, preferably max. 10% or even more preferably max. 7% of their width.

In a preferred design the lateral distance between the individual targetarrangements d is

1 mm≦d≦230 mm, where preferably

7 mm≦d≦20 mm.

Width B of the individual target arrangements is preferably

60 mm≦B≦350 mm, more preferably

80 mm≦B≦200 mm

and their length L preferably

400 mm≦L≦2000 mm.

The length of the individual target arrangements relative to their widthis at least the same, preferably considerably longer. Although thesputtering surfaces of the individual target arrangements are flat orpre-shaped and preferably arranged along one plane, it is feasible toarrange the lateral sputtering surfaces closer to the substrate to becoated than the ones in the middle, possible also inclined, in order tocompensate any edge effects on the film thickness distribution, ifnecessary.

The electrons of the magnetron plasma circulate along the "race tracks"in a direction defined by the magnet field and the electrical field inthe target surface area. It has been observed that the routing of theelectron path or its influence upon it and consequently the influence onthe resulting erosion furrows on the target surfaces can be specificallyoptimized by creating the magnet field along the longitudinal axes ofthe target arrangements and by varying the shape of said field not onlywith respect to time but also location. With a magnet frame--preferablyone each, and also preferably one permanent magnet frame each--this ispreferably achieved by positioning and/or by the selected strength ofthe magnets on the frame, and/or by providing magnet arrangements eachbelow the target arrangements, preferably said permanent magnet drums,by correspondingly varying the strength and/or relative position of themagnets on the magnet arrangement. As the electrons move in a circularpath in accordance with the magnet field polarity, it has been observedthat apparently due to drift forces the electrons, in particular in thenarrow side areas of the target arrangements and in accordance with thedirection of their movement, the electrons in corner areas that arediagonally opposite are forced outward. For this reason it is proposedthat with the provided magnet frame the field strength created by theframe magnets which are specular symmetrical to the target "rectangle"diagonal be preferably designed with a locally different shape.

In a preferred design version of the source according to the inventionthe target arrangements are fixed by means of linear bayonet catches, inparticular in combination with their cooling via pressure loaded foilsof the aforementioned type. In this way the arrangements can be veryeasily replaced after the pressure in the cooling medium channels hasbeen relieved; the greater part of the target arrangement back sideremains accessible for cooling and no target arrangement fixing devicesare exposed toward the process chamber.

A preferred source according to the invention features more than twotarget arrangements, preferably five or more.

By using a magnetron sputtering source according to the invention on asputter coating chamber on which, with a clearance from the latter, asubstrate holder for at least one, preferably planar substrate to besputter coated is provided, it is possible to achieve an optimally smallratio V_(QS) between the sputtered source surfaces F_(Q) and thesubstrate surface F_(S) to be sputtered, where:

V_(QS) ≦3, preferably

V_(QS) ≦2, where particularly preferred

1.5≦V_(QS) ≦2.

This significantly increases the utilization efficiency of the source.In a sputter coating chamber according to the invention with said sourcethis is achieved to an even higher degree by choosing the distance Dbetween the virgin surface of the magnetron sputtering source and thesubstrate in such a way that it is essentially equal to the width of alongitudinal target arrangement, preferably

60 mm≦D≦250 mm,

preferably 80 mm≦D≦160 mm

On a vacuum coating system according to the invention with a sputtercoating chamber according to the invention and consequently themagnetron sputtering source according to the invention, the targetarrangements are each connected to an electrical generator or currentsources, where said generators can be controlled independently of eachother.

The sputter coating system according to the invention with at leastthree long target arrangements is preferably operated in such a way thatthe two outer target arrangements are operated with 5 to 35% moresputtering power, preferably with 10 to 20% more sputtering power thanthe inner target arrangements. The aforementioned "scanning" of thetarget arrangements with respect to the position of the plasma zones andin particular the preferred "wobbling" of the apex of the tunnel magnetfields and consequently the plasma density distribution, preferablyrealized by means of said magnet drums in pendulum operation, ispreferably performed with a frequency of 1 to 4 Hz, preferably approx. 2Hz. The pendulum amplitude of the drum is preferably φ≦π/4 ( φ meaningthe peak value for φ). The coating thickness distribution on thesubstrate is further optimized through an appropriate design of thepath/time profiles of said shift in position.

It should be emphasized that for this purpose also the generatorsconnected to the target arrangements can be controlled for outputtingmutually dependent, time modulated signals.

In addition the electrical supply of the target arrangements and/or thedistributed gas inlets and/or the magnet field distribution arecontrolled in such a way or modulated in time in such a way that thedesired, preferably homogenous, film thickness distribution on thesubstrate is achieved.

The magnetron sputtering source is preferably operated with a powerdensity p of

1 W/cm² ≦p≦30 W/cm²,

in particular for reactive film deposition, preferably from metallictargets, and in particular ITO films with

1 W/cm² ≦p≦5 W/cm²,

and for sputter coating metal films preferably with

15 W/cm² ≦p≦30 W/cm².

As has been recognized in conjunction with the development of saidmagnetron sputtering source according to the invention, it is basicallyadvantageous, in particular with target plate arrangements that aresignificantly longer than wide, to design the magnet field strength ofthe magnetron field, viewed in the longitudinal direction of the targetarrangements and in particular their lateral areas, with a locallydifferent shape.

However, this insight is generally applicable to long magnetrons.

For this reason it is proposed for a long magnetron source according tothe invention which comprises a time-variable, preferably moving magnetsystem, to assign a magnet frame to the target arrangement, preferably apermanent magnet frame where the field strength of the frame magnetsmeasured in one given chamber direction, is designed locally differentalong the longitudinal side of the target arrangements. For compensatingsaid drift forces acting on the circulating electrons it is proposed todesign this field strength locally different essentially specularsymmetrical to the target diagonal.

The present invention under all its aspects is in particular suited tosputter coating substrates, in particular large-surface and preferablyplane substrates by means of a reactive process, preferably with an ITOfilm (Indium Tin Oxide). The invention is also suited to coatingsubstrates, in particular glass substrates, used in the production offlat panel displays, in particular TFT or PDP panels, where basicallythe possibility is opened to highly efficiently sputter coat also largesubstrates, for example, also semiconductor substrates, with minimalreject rates either by means of a reactive or non-reactive process, butin particular also reactive.

Especially in sputter coating processes, in particular in ITO coating,low discharge voltages for achieving high film quality, in particularlow film resistances, also without tempering steps, are essential. Thisis achieved by means of the source according to the invention.

It also achieves effective suppression of arc discharges.

The invention is subsequently explained based on illustrated examples:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Magnetron sputtering source according to the invention,electrically operated in a first version;

FIG. 2 Schematic representation of the sputtering source according toFIG. 1 in another electrical circuit configuration;

FIG. 3 Another circuit configuration of the sputtering source accordingto the invention, shown analogously to FIG. 1;

FIG. 4 Croes-sectional detail of a magnetron sputtering source accordingto the invention;

FIG. 5 Top view of a linear bayonet catch is used preferably on thesource according to FIG. 4;

FIG. 6 Simplified top view of a detail of a magnetron source accordingto the invention;

FIG. 7 Top view of a preferred design version of a permanent magnet drumpreferably provided according to FIG. 6 on the magnetron sputteringsource according to the invention;

FIG. 8 Schematic representation of a sputter coating system according tothe invention;

FIG. 9 Erosion profile on a target arrangement of the source accordingto the invention;

FIG. 10 Distribution of the sputtered material, determined on a sourceaccording to the invention with five target arrangements;

FIG. 11 Film thickness relief pattern on a 530×630 mm² glass substratecoated by a source according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 schematically shows a magnetron sputtering source 1 according tothe invention in its basic configuration. It comprises at least two, oras illustrated, for example, three long target arrangements 3a to 3c.The additional devices to be provided on a magnetron sputtering source,such as the magnet field sources, cooling facilities, etc. are not shownin FIG. 1. Source 1 has separate electrical connections 5 on each targetarrangement. For example, strip shaped anodes 7a, 7b are providedpreferably between the longitudinally spaced target arrangements 3.

Because the target arrangements 3 are electrically insulated from eachother and have separate electrical terminals 5, independent electricalwiring as subsequently also described in conjunction with FIGS. 2 and 3is possible.

As shown in FIG. 1 each target arrangement 3 is connected to a generator9, each of which generators can be controlled independently of eachother and which do not necessarily have to be of the same type. As shownschematically the generators can be all of the same type or implementedin any mixed combination of DC generators, AC generators, AC and DCgenerators, generators for outputting pulsed DC signals, or DCgenerators with intermediate generator output, and with the chopper unitfor the corresponding target arrangement. With respect to their designand operating principle full reference is made to said EP-A-0 564 789 orU.S. application Ser. No. 08/887 091.

Also with respect to the electrical operation of the anodes 7 there iscomplete freedom in that they are operated either with DC, AC, DC withsuperposed AC or pulsed DC voltage, or possibly via one of the saidchopper units, or, as shown at 12a, connected to reference potential. Byvarying the electrical cathode or target arrangement mode and possiblyalso the electrical anode mode, distributed across the source surfaceformed by the target arrangements, the distribution of sputteredmaterial and consequently the distribution on a substrate (not shown)arranged above the source can be adjusted.

Generators 9 can be time modulated with mutual dependence, as shown bythe modulation inputs MOD, in order to specifically modulate in the formof a travelling wave, the electrical operating conditions above thetarget arrangements.

FIGS. 2 and 3 show, with the same position symbols, additionalelectrical wiring arrangements of source 1 according to the invention atwhich (not shown) an anode arrangement is-not necessary.

As shown in FIGS. 2 and 3 the target arrangements 3 are connected inpairs to the inputs of AC generators 15a, 15b or 17a 17b respectively,where also here generators 15 or 17 can optionally output AC superposedDC signals or pulsed DC signals. Again, generators 15, 17 are modulated,if desired, for example an AC output signal practically as carriersignal, with an amplitude modulation.

Whereas according to FIG. 2 one target arrangement 3b each is connectedto an input of one of the generators 15a and 15b, target arrangements 3as shown in FIG. 3 are connected in pairs via generators 17. As shownwith dashed lines at 19 it is possible, in the sense of "common mode"signals, as well as in the design according to FIG. 2 as well as the onein FIG. 3, to jointly connect individual target arrangement groups todifferent potentials. If a wiring technique according to FIG. 2 or 3 ischosen, the generators in a preferred design version are operated with afrequency of 12 to 45 kHz. With respect to a "common mode" potential, asfor example, the mass potential shown in FIG. 2, target arrangementsconnected in pairs to a generator are alternately connected to positiveand negative potentials.

As can be seen from the diagrams in FIGS. 1 to 3 the magnetron sourceaccording to the invention allows very high flexibility for electricallyoperating the individual target arrangements 3 and consequently tospecifically design the distribution of the sputtered material inprocess chamber 10 and the deposition on a substrate.

FIG. 4 is a cross-sectional detail of a magnetron sputtering sourceaccording to the invention in a preferred version. As shown in FIG. 4the target arrangements comprise one target plate 3_(a1) or 3_(b1) eachmade of the material to be sputtered and which are bonded to one backingplate each 3_(a2) or 3_(b2) respectively. With the aid of the linearbayonet catches 20 the target arrangements 3 are fixed on their lateralperiphery and/or in their center area to a metallic cooling plate 23.

The design of the linear bayonet catches is illustrated in FIG. 5according to which a hollow rail is provided either on targetarrangement 3 or on cooling plate 23, which rail has a U-shapedcross-section, with inwardly bent U-legs 27 on which recesses 29 arecreated at a certain distance. On the other of the two parts, preferablyon target arrangement 3, a linear rail with a T-shaped cross-section isprovided on which the ends of the cross-member 33 feature protrusions34. By inserting the protrusions 34 into the recesses 29 and by linearshifting in direction S the two parts are interlocked. It is possible,of course, in the sense of reversal, to create protrusions on the hollowrails that engage into corresponding recesses on rail 31.

The target arrangements 3 are clamped to the cooling plate 23 only whenpressure is applied by the cooling medium in cooling channels 35 ofcooling pate 23. These channels 35 extend along the predominantly flatarea of the target arrangement surface facing cooling plate 23. Coolingchannels 35, pressurized by a liquid cooling medium under pressure asdescribed above, are sealed against the target arrangement by a foiltype membrane 37, as is described in detail, for example, in CH-A-687427 of the same applicant. Under pressure of the cooling medium foils 37press tightly against the bottom of plate 3_(a2) or 3_(b2) respectively.Only when the cooling medium is put under pressure does the targetarrangement become rigidly clamped in the bayonet catch. For removingthe target arrangement 3 the complete cooling system or thecorresponding cooling system section is pressure relieved, as a resultof which the target arrangements can be easily pushed out and removed orreplaced.

Anode strips 39 are positioned on the longitudinal side of the targetarrangements 3. The anode strips as well as cooling plate 23 are mountedon a supporting base 41 which preferably is made at least partially ofinsulating material, preferably plastic. Base 41 separates the vacuumatmosphere in process chamber 10 from the ambient or normal atmospherein space 11.

On the atmosphere side of base 41, for example, two permanent magnetdrums 43, extending along the longitudinal dimension of the targetarrangement, are supported in a rotating fashion and are driven withpendulum motion by motors (not shown). In pendulum motion theypreferably perform a 180° angle pendulum movement--ω43. In the permanentmagnet drums 43, permanent magnets 45 are mounted along the longitudinaldrum dimension, preferably diametrically.

Also on the atmosphere aide of base 41 one permanent magnet frame 47 foreach target arrangement 3 is mounted which essentially runs below andalong the periphery of the corresponding target arrangement 3, as shownin FIG. 6.

In particular along the longitudinal sides of the target arrangementsgas inlet lines 49 terminate as shown in FIG. 6, which can be controlledcompletely independently of each other, preferably in rows, with respectto the gas flow, as shown with dashed lines in FIG. 4. This isschematically shown in FIG. 4 with servo valves 51 that are provided ina connection between lines 49 and a gas tank arrangement 53 with workinggas such as argon and/or with a reactive gas.

With respect to the operation and design of the permanent magnet drum 43we again refer fully to the disclosure content of EP-0 603 587 or U.S.Pat. No. 5,399,253 respectively.

FIG. 6 shows a simplified top view detail of a magnetron source in FIG.4 according to the invention. As already described based on FIG. 4 apermanent magnet frame 47 is installed below each target arrangement 3.Preferably the magnet frame 47 is designed in such a way that whenviewed in a chamber direction, for example according to H_(z) in FIG. 4,the magnet field generated by the permanent magnet frame changes locallyalong the longitudinal sides of the target arrangements 3, as shown inFIG. 6 with x. In a preferred design the magnets arranged on thelongitudinal legs 471₁ and 471₂ of frame 47 are subdivided in to zones,for example, four zones as shown in FIG. 6. In the diagram of FIG. 6 thefield strength of the permanent magnets in the individual zones Z1 to Z4is qualitatively shown through coordinate x and thereby the fieldstrength distribution in the x direction. In addition the permanentmagnet dipole directions are shown in the corresponding zones 2.

On legs 471₁, 2, the same permanent magnet zones are preferablyprovided, however, specular symmetrical with respect to the diagonal D₁of the long target arrangement 3.

Through a specific design of the local magnet field distribution that isachieved through the permanent magnet frames 47 on the targetarrangements 3 it is possible to optimize the path of the circulatingelectrons and consequently the location and shape of the erosionprofiles on the individual target arrangements. This in particular bytaking into consideration the path deformations caused by drift forces.On the.broad sides of the target frames 47 permanent magnet zones Z_(S)are provided which preferably correspond to zone Z₂. As mentioned beforealso a single-target source according to FIGS. 4, 6 and 7 is inventive.

Magnet fields H which vary locally in the x direction above thecorresponding target arrangements 3 which varies also as a function ofthe magnet drum pendulum motion and varies also in time, is specificallydesigned by choosing the field strength of the provided permanentmagnets such as in zones Z₁, Z₂, Z₄ and/or through the spatial dipoleorientation such as in zone Z₃, and/or in the position (distance fromthe target arrangement).

As mentioned, at least two permanent magnet drums 43 are preferablyprovided on each of the target arrangements 3 provided on the sputteringsource according to the invention. One such drum is shown in FIG. 7.

Preferably different permanent magnet zones, for example, Z'₁, to Z'₄,are provided also on drums 43. FIG. 7 qualitatively shows theprogression of the locally varying permanent magnet field H_(r) (x)along the provided drums, in accordance with the preferred design.

On the source according to the invention the location and timedistribution of the sputter rate is optimized through specific locationand/or time distribution of the electrical supply of the individualtarget arrangements and/or specific location and/or time variation ofthe magnetron magnet field on the individual target arrangements and/orthrough specific location and/or time variation or design of the gasinflow conditions on the inlet openings 49. In the preferred designversion that has been explained based on FIGS. 4 to 7, these variablesare preferably exploited in combination in order to specifically design,preferably homogeneously, the film thickness distribution on a substrateto be sputter coated, in particular a flat substrate.

FIG. 8 schematically shows a sputter coating system 50 according to theinvention with a sputter coating chamber 60 according to the inventionin which is also schematically shown a magnetron sputtering source 10according to the invention. The schematically shown source 10 asimplemented in a preferred version features six target arrangements 3and is also preferably designed as has been explained based on FIGS. 4to 7. The source according to the invention with its target arrangementsis operated with independent electrical supplies that can possibly bemodulated, as shown in block 62. Further, the gas inflowconditions--which can possibly be modulated, in particular along thelongitudinal dimensions of the target arrangements as shown with servovalve 64, are selectively set in order to admit a working and/orreactive gas from gas tank 53 into the process chamber.

With drive block 65 the drive--which can possibly be path/timemodulated--for the permanent magnet drums on the source according to theinvention is shown on which, preferably selectively, the desired drumpendulum motions can be set.

In chamber 60 according to the invention a substrate holder 66 isprovided, in particular for holding a flat substrate to be coated. Basedon the capabilities offered by the source according to the invention ofoptimally setting the time and location distribution of the materialsputtered off by source 10, in particular a uniform distribution thathas been averaged over time, in particular also in the edge zones of thesource, it is possible to make the ratio V_(QS) of the sputteringsurface F_(Q) of the source to the substrate surface F_(S) to be coatedastonishingly small, preferably

V_(QS) ≦3,

preferably

V_(QS) ≦2,

and even more preferably

1.5≦V_(QS) 2.

This ratio shows that the material sputtered off the source is used veryefficiently because only correspondingly little of the sputteredmaterial is not deposited on the substrate surface. This efficiency isfurther enhanced because distance D--due to the large-surfacedistributed plasma coating of the source--between the substrate surfacesto be sputtered and the virgin surface of the magnetron source 10, canbe selected very small, essentially equal to width B (see FIG. 4) of thesputter surfaces on target arrangements 3 and preferably

60 mm≦D≦250 mm

preferably

80 mm≦D≦160 mm.

Through said small distances D a high deposition rate is achieved withhigh sputtering efficiency which results in a highly economical coatingprocess.

On the system shown in FIG. 8 the outermost target arrangements arepreferably operated by generators 62 with higher sputtering power,preferably 5 to 35% higher, and even more preferably with 10 to 20%higher sputtering power than the inner target arrangements. Thepermanent magnet drums provided on source 10 according to FIG. 4 arepreferably operated in pendulum mode with a pendulum frequency of 1 to 4Hz, preferably with approx. 2 Hz.

The magnetron sputtering source, sputtering chamber or system, inparticular in preferred operation, are particularly suitable formagnetron sputter coating large-surface, in particular flat substrates,with a high-quality film, with desired distribution of the filmthickness, in particular a homogenous film thickness distribution incombination with high process economy. A significant contribution tothis is made by the large-surface, homogeneously distributed processconditions on the source according to the invention. As a consequencethe invention can be used for coating large-surface semiconductorsubstrates, but in particular for coating substrates of flat displaypanels, in particular TFT or PDP panels. This invention is in particularused for reactive coating of said substrates, in particular with ITOfilms or for metal coating said substrates through non-reactive sputtercoating. In the subsequent examples preferred sizes of the sourceaccording to the invention or the chamber or the system are summarized.

1. Geometry

1.1 On the Source

Lateral distance d according to FIG. 4: maximum 15%, preferably maximum10%, even more preferably maximum 7% of the width dimension B of thetarget arrangements and/or

1 mm≦d≦230 mm, preferably

7 mm≦d≦20 mm.

Virgin surfaces of the target arrangements along one plane;

Width B of the target arrangements:

60 mm≦B≦350 mm, preferably

80 mm≦B≦200 mm.

Length of the target arrangements L: at least B, preferably considerablylonger, preferably

400 mm≦L≦2000 mm.

End area of the targets: e.g. semicircular.

1.2 Source/subutrate:

Ration V_(QS) of the dimension of sputtering surface F_(Q) to thedimension of the substrate surface F_(S) to be coated:

V_(QS) ≦3, preferably

V_(QS) ≦2, or preferably even

1.5≦V_(QS) ≦2.

Smallest distance of the virgin source surfaces/coating surfaces D:

60 mm≦D≦250 mm, preferably

80 mm≦D≦160 mm.

Substrate sizes: for example 750×630 mm, coated with a source having asputtering surface of: 920×900 mm, or

Substrate size: 1100×900 mm, with a source having a sputtering surfaceof: 1300×1200 mm.

1.3 Cooling:

Ratio sputtering surface to cooling surface V_(SK) :

1.2≦V_(SK) ≦1.5.

2. Operating Variables

Target temperature T:

40° C.≦T≦150° C., preferably 60° C.≦T≦130° C.

Sputter power per unit of sputtering surface: 10 to 30 W/cm², preferably15 to 20 W/cm².

Outermost target arrangements on each side, preferably with 5 to 35%more sputter power, preferably 10 to 20% more sputter power per unit ofsurface.

Pendulum frequency of the magnet drums: 1 to 4 Hz, preferably approx. 2Hz.

Results

The following deposition rates were achieved:

ITO: 20 Å/sec.

Al: 130 to 160 Å/sec.

Cr: 140 Å/sec.

Ti: 100 Å/sec.

Ta: 106 Å/sec.

FIG. 9 shows the erosion profile on a 15 cm wide sputtering surface in atarget arrangement on the source according to the invention. Due to theextremely uniform erosion the "race tracks" or erosion profiles arebarely recognizable.

FIG. 10 shows the resulting coating rate distribution of ITO sputtering,based on a source according to the invention with five targetarrangements, each with a sputtering surface width B of 150 mm. In thisdistribution, film thickness deviations of only ±3.8 are achieved on asubstrate arranged at a distance D of 120 mm from the source surface.

In FIG. 11 the resulting film thickness distribution on a large-surfaceglass substrate is shown which has been coated as follows:

    ______________________________________                                        Total sputtering power P.sub.tot :                                                                   2        kW                                            Sputtering time:       100      sec.                                          Deposition rate R: 26 Å/sec., relative:                                                          13       Å/sec. kW                                 Source with six target arrangements of which the                              outermost arrangements have been operated with                                an elevated sputter power of 10 or 15%                                        respectively (p.sub.1, p.sub.6):                                              Substrate size:        650 × 550                                                                        mm                                            ______________________________________                                    

In FIG. 11 the edge zones of the substrate that were above the targetarrangements operated with elevated sputter power are marked. In the ITOcoating process the film thickness deviation relative to the mean filmthickness of 267 nm was ±6.3%.

The present invention avoids the following disadvantages of knownsputtering sources, in particular with respect to the coating oflarge-surface workpieces:

Because according to the invention a uniform distribution of the processconditions over a large magnetron sputtering surface is possible withhigh deposition rate and high sputter rate utilization, high economy isachieved when coating large-surface substrates, or possibly in thesimultaneous coating of many individual substrates.

Because on the source according to the invention simultaneous sputteringover a large surface takes place, better film thickness distribution onthe substrate is achieved and arcing is prevented.

As the problem of reactive gas distribution and/or target erosiondistribution is solved in a homogenizing sense, the substrates to becoated can be positioned much closer to the source and have much largercoating surfaces relative to the source surface, which improves theeconomy of a sputter coating system that is equipped with a sourceaccording to the invention.

The problem of plasma density differences between the target center andtarget periphery occurring on large-surface targets due to missinganodes in the target center is remedied.

The source can be adapted flexibly to the corresponding sizerequirements by means of modular target arrangements.

The problem occurring with large-surface targets where there is reactiveprocess gas starvation in the middle of the target, is solved becausethe gas inlets 49 are distributed across the actual source surface.

Because (see FIG. 4) the base (41) is between process vacuum andatmospheric pressure it in no longer necessary to provide a heavycooling plate (23) that can absorb this load. As a result the sourcebecomes less elaborate and better penetration of the fields of themagnet arrangements (47, 43) located below the target arrangement (3) isachieved.

Through the selective control of the following distributions:

by time and/or location, electrical operation of the target arrangements

by time and/or location, magnetic operation of the target arrangements

by time and/or location, gas inlet

it is possible to optimally adjust the film thickness distribution,especially homogeneously, of large-surface substrates.

Due to the provided bayonet catches in conjunction with the clamping ofthe target arrangements via the cooling media pressure extremely simpleand fast exchange of the target arrangements is possible andlarge-surface, efficient cooling is achieved.

Due to the bayonet catches provided below the sputtering surfaces nofixing elements, and in particular no fixing elements made ofnon-sputtering material, are accessible from the process chamber.

What is claimed is:
 1. A sputter source with at least two electricallymutually isolated stationary bar-shaped target arrangements mounted onealongside the other and separated by respective slits, each of saidtarget arrangements comprising a respective electric pad so that each ofsaid target arrangements may be operated electrically independently fromthe other target arrangement and wherein each target arrangementcomprises a controlled magnet arrangement generating a time-varyingmagnetron field upon the respective target arrangement and wherein themagnet arrangements are controlled independently from each other.
 2. Thesource of claim 1 further comprising an anode arrangement comprisinganodes alongside and between said target arrangements and/or along thesmaller sides of said target arrangements.
 3. The source of claim 1,wherein magnet arrangements comprise a frame with electrical and/orpermanent magnets along said target arrangements.
 4. The source of claim1, wherein said magnet arrangements respectively generate atunnel-shaped magnetic field upon respective target arrangements with atime-varying apex of said tunnel-shaped magnetic field.
 5. The source ofclaim 1, wherein said magnet arrangements each comprise at least twodrivingly rotatable or rotatably pivotable drums with permanent and/orelectric magnets.
 6. The source of claim 5, wherein said drums arearranged along a length of said bar-shaped target arrangements.
 7. Thesource of claim 1, wherein said target arrangements are mounted on abase, said base being adjacent each of said target arrangements andincluding a cooling medium channel arrangement sealingly covered by afoil.
 8. The source of claim 7, wherein said base is adapted towithstand a pressure difference of sputtering vacuum to surroundingatmosphere pressure.
 9. The source of claim 11, wherein said targetarrangements are mounted on a base, said magnet arrangements comprisingstationary magnets mounted into electrically isolating material of saidbase.
 10. The source of claim 1, wherein said target arrangements aremounted on electrically isolating material of a base.
 11. The source ofclaim 1, comprising an anode arrangement mounted on electricallyisolating material of a base.
 12. The source of claim 1, wherein saidmagnet arrangements comprise mechanically moveable permanent magnetsand/or electro-magnets beneath said target arrangements, said magnetsbeing mounted on electrically isolating material of a base.
 13. Thesource of claim 1, further comprising a base whereon said targetarrangements are mounted, said base comprising cooling medium channelsdefined in electrically isolating material of said base.
 14. The sourceof claim 13, wherein bottom surfaces of said cooling medium channels areformed by metallic plate material.
 15. The source of claim 1, furthercomprising a gas inlet arrangement with gas inlet openings arrangedalongside said target arrangements and communicating with a gasdistribution system.
 16. The source of claim 1, wherein said targetarrangements are distant from each other by a distance of at most 15% ofthe width of one of said bar-shaped target arrangements.
 17. The sourceof claim 16, wherein said distance is at most 10% of said width.
 18. Thesource of claim 17, wherein distance is at most 7% of said width. 19.The source of claim 1, wherein said bar-shaped target arrangements havea length which is significantly larger than their width.
 20. The sourceof claim 19, wherein said length, identified as L, is in the range:400mm≦L≦2000 mm.
 21. The source of claim 1, wherein said targetarrangements are distant from each other by distance d, wherein:1mm≦d≦230 mm.
 22. The source of claim 21, wherein:7 mm≦d≦20 mm.
 23. Thesource of claim 19, wherein there is a width B of respective ones ofsaid target arrangements:60 mm≦B≦350 mm.
 24. The source of claim 23,wherein:80 mm≦B≦200 mm.
 25. The source of claim 1, wherein sputteringsurfaces of said target arrangements in unsputtered condition arealigned substantially along a plane.
 26. The source of claim 1, whereinsaid magnet arrangements generate a magnetic field which, considered atmoments of time, locally varies along the length of said bar-shapedtarget arrangements.
 27. The source of claim 1, wherein a frame withmagnets surrounds at least some of said target arrangements and saidmagnets in said frame and alongside said at least some of said targetarrangements are of mutually different magnetic strength.
 28. The sourceof claim 1, wherein at least two driving pivotable magnet drums aremounted parallel to each other, beneath and along said targetarrangements and comprise magnets the position and/or the strength ofwhich magnets varying in the direction of axes of said magnet drums. 29.The source of claim 28, wherein said magnets of said magnet drums arepermanent magnets.
 30. The source of claim 1, further comprising a framesurrounding at least a part of said target arrangements, said framecomprising magnets arranged along the length of said frame and being ofdifferent magnetic strengths considered along said length, magneticstrengths of said magnets being substantially symmetrical to a diagonaldirection of said frame.
 31. The source of claim 30, wherein saidmagnets of said frame are permanent magnets.
 32. The source of claim 1,wherein said target arrangements are mounted to a base via linearlybayonet links.
 33. The source of claim 1, comprising more than two ofsaid target arrangements.
 34. The source of claim 31, comprising atleast five of said target arrangements.